Tina and her daughters are all obese - but it's not their fault, it's their genes

To many of us who struggle with our weight, the problem is obvious: it’s our genes. After all, how else to explain those people who manage to stay slim despite gobbling down cakes and stodgy pizzas.

And now the emerging science of nutrigenomics seems to back this up.

Nutrigenonomics is the study of the relationship between diet and specific genes, and increasingly the evidence from this work suggests that some people are born with a greater propensity to gain weight.

Inherited problem: Tina with daughters Karen (left) and Lisa were found to have 'risk' genes

Scientists have identified genes that influence the intensity of your hunger pains, how well your brain gets the ‘full-up’ signals from your stomach, where your body is more likely to store fat — even your sense of taste (whether you have a genetic preference for sweet or fatty foods).

Just last week, it was revealed that a mutated version of a gene that almost a third of women are thought to have fuels the development of fatty tissue — those with it are two-and-a-half times more likely to put on more than a stone.

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‘In the past five years, there have been significant developments in technology that has identified risk versions of around 70 genes people can carry, putting them at an increased risk of obesity,’ says Dr Giles Yeo, director of genomics at the Medical Research Council’s Metabolic Diseases Unit at the University of Cambridge.

Dr Yeo has identified two genes that affect the messages sent to tell our brains our stomach is full. ‘Testing for the genes is cutting edge, so it’s very exciting,’ he says. ‘Having a “risk” version of one of these genes won’t have an effect alone, but a number of subtle differences to many genes can amount to an increased risk of weight problems.’

But can these scientific insights help women such as Tina McConnon? She has struggled with her weight for years. ‘As a child I was chubby but the weight really piled on after I had children — I ballooned to a size 26 and I’d get out of breath just getting dressed,’ says Tina, 59, a retired nurse from Stevenage, Herts.

At 5ft 1.5in, she weighed 15st 10lb — giving her a body mass index (BMI) of 40.9 (‘healthy’ is 18.5 to 24.9 — Tina is officially obese). She ate huge portions of her favourite foods — including refined carbohydrates such as white bread and white pasta — guzzled litres of sugary juices and snacked on chocolate.

She would often feel hungry an hour after a big meal and then eat again. But she was adamant she didn’t eat more unhealthily than some of her slim friends.

‘I’ve been on diets off and on since I was 26, but I found it impossible to stick to them for long. I thought my weight struggles could have been genetic because it seemed to be a common trend in my family.’ Tina’s mother, brother, aunt and grandmother were all large.

Then last December, Tina and her daughters Lisa, 37, and Karen, 39, had their genes analysed for Channel 4’s Fat Family Tree programme, to find out if it could help explain their weight gain. Dr Yeo created the test, designed to check for 70 genes linked to weight gain. Tina was around 6st overweight — ‘and the biggest I’d ever been’.

Tina had been on diets off and on since she was 26

‘I felt uncomfortable and
self-conscious, but my biggest fear was ending up like my mum and my
brother, Gordon, who were both very overweight and died from diabetes
when they were in their early 60s.

‘It was very worrying seeing my daughters getting bigger and bigger — I didn’t want them going the same way.’

Lisa, a milliner, tipped the scales at 22st 4lb (at 5ft 8in, her BMI was 47.4), while Karen, a child support worker, weighed 20st 13lb (at 5ft 6in, her BMI was 47.3).

‘I felt like I’d let them get fat,’ says Tina, who also has a son, Christopher, 35, with her husband Patrick, 62, a gas and heating engineer (neither of the men in the family has a major weight problem).

Her weight had already had an effect on Tina’s health — she’d had high blood pressure for eight years and was taking beta-blockers — when tests for the programme revealed she also had high cholesterol and type 2 diabetes. The gene tests suggested it wasn’t just lack of willpower that had thwarted the family’s efforts to lose weight. Dr Yeo found that all three women had inherited numerous genes linked to obesity — with Tina having the ‘risk’ (ie. weight-gain) versions of 26 out of the 70 genes.

They all had genes linked to storing fat around their stomachs (causing an apple-shaped figure — linked to an increased risk of type 2 diabetes and heart disease) — scans confirmed they had stored fat here.

The trio also had two ‘risk’ genes that effectively blocked signals to the brain that the stomach is full (causing people to over-eat), and subtle changes to another gene, which also controls food intake. There are also genes that control our brain’s response to food — some versions mean people may need to consume more of a ‘rewarding’ food to get the same effect of satisfaction.

‘Humans evolved to eat as much as possible because as cavemen we didn’t know when our next meal would be, says Dr Yeo. Sweet and high-fat foods have the most calories, giving us the most energy — which would have been advantageous to eat then.

‘Nowadays, of course, we don’t need to hunt but that doesn’t stop our genetic drive and the way we evolved to like sweet, fatty foods.’

But in some people, this drive is greater. ‘Slight genetic changes put a person at risk of having an increased liking for food with higher energy.

‘Eating less will cause weight loss but, depending on your genetic make-up and these subtle changes, some people, such as the McConnons, find it more difficult to adhere to diets and stop eating than others.

‘When we understand more about what these genes do, we can identify at-risk people and advise them to make changes,’ says Dr Yeo. ‘At the moment, these kinds of costly gene tests are not available from the NHS, although there are private companies that offer versions of them.

‘The cure is still the same — if you reduce food intake you can beat your genetic burden, although your genes may make things more difficult for you.’

After their testing, Tina and her daughters were given a diet to target their weaknesses identified by their fat risk genes, and they were also instructed to walk 10,000 steps every day.

Because their genes make them more likely to feel hungry, they were told to eat foods including whole grains, beans, lentils and rye bread to keep them fuller for longer.

Fermentable carbo-hydrates, such as barley, asparagus and oats, which trigger the part of the brain that tells us when we are full, are also recommended, in order to target their problem DNA.

‘Knowing what genes I have, I can see why I struggled to stick to my diets,’ says Tina. ‘But I now know I need to keep to my new eating plan and proper portion sizes, or I’ll be ill. The food I’m eating now fills me up more than what I used to eat so it’s working well.’

Tina has lost nearly 2st, is now a size 18 and her diabetes has gone into remission. Lisa has lost 3st; Karen just over two.

‘I have more energy and confidence, my blood pressure and cholesterol are now normal and I’m walking, decorating and gardening, which would have been a struggle before,’ Tina says.

‘Knowing I had these problem genes made me determined to overcome them. The experience has changed my life.’